WARNING in u32_change

Status: upstream: reported C repro on 2026/02/22 20:25
Bug presence: origin:upstream
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+b98f25656b791725fc13@syzkaller.appspotmail.com
First crash: 207d, last: now
Bug presence (3)
Date Name Commit Repro Result
2026/05/30 linux-6.6.y (ToT) 0a40c6fbd105 C [report] WARNING in u32_change
2026/02/23 upstream (ToT) 6de23f81a5e0 C [report] WARNING in u32_change
2026/05/30 upstream (ToT) 670b77dfebe7 C Didn't crash
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in u32_change (2) net -1 syz, C error 760 156d 198d 29/29 fixed on 2026/05/21 07:50
upstream WARNING in u32_change net -1 syz, C 28 1357d 1454d 22/29 fixed on 2023/02/24 13:50
linux-6.1 WARNING in u32_change -1 syz, C 437 4h50m 207d 0/3 upstream: reported C repro on 2026/02/22 19:31
Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/06/18 00:29 2h26m fix candidate upstream OK (0) job log

Sample crash report:
netlink: 40 bytes leftover after parsing attributes in process `syz.0.17'.
------------[ cut here ]------------
memcpy: detected field-spanning write (size 32) of single field "&new->sel" at net/sched/cls_u32.c:855 (size 16)
WARNING: CPU: 0 PID: 5928 at net/sched/cls_u32.c:855 u32_init_knode net/sched/cls_u32.c:855 [inline]
WARNING: CPU: 0 PID: 5928 at net/sched/cls_u32.c:855 u32_change+0x1df2/0x2860 net/sched/cls_u32.c:921
Modules linked in:
CPU: 0 PID: 5928 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/08/2026
RIP: 0010:u32_init_knode net/sched/cls_u32.c:855 [inline]
RIP: 0010:u32_change+0x1df2/0x2860 net/sched/cls_u32.c:921
Code: f8 eb 59 e8 e0 58 cf f8 c6 05 28 eb be 05 01 b9 10 00 00 00 48 c7 c7 00 62 c8 8b 4c 89 f6 48 c7 c2 80 62 c8 8b e8 7e 25 99 f8 <0f> 0b e9 10 ef ff ff e8 b2 58 cf f8 eb 24 e8 ab 58 cf f8 c6 05 a0
RSP: 0018:ffffc9000329ed60 EFLAGS: 00010246
RAX: 91d23fde175ee900 RBX: ffff88806b396800 RCX: ffff888024013c00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc9000329eef8 R08: ffffc9000329e967 R09: 1ffff92000653d2c
R10: dffffc0000000000 R11: fffff52000653d2d R12: 1ffff92000653dbc
R13: ffff88806b396ce8 R14: 0000000000000020 R15: 0000000000000001
FS:  000055556f6e9500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000006040 CR3: 00000000781c7000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 tc_new_tfilter+0x1109/0x1840 net/sched/cls_api.c:2418
 rtnetlink_rcv_msg+0x892/0xf90 net/core/rtnetlink.c:6475
 netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x61b/0x980 net/socket.c:2595
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
 __sys_sendmmsg+0x2ca/0x510 net/socket.c:2735
 __do_sys_sendmmsg net/socket.c:2764 [inline]
 __se_sys_sendmmsg net/socket.c:2761 [inline]
 __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2761
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f986b19e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff07601088 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f986b425fa0 RCX: 00007f986b19e159
RDX: 04000000000001f2 RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007f986b23503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f986b425fac R14: 00007f986b425fa0 R15: 00007f986b425fa0
 </TASK>

Crashes (315):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/13 06:36 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/04 17:50 linux-6.6.y 924b4a879cbb 197909be .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/23 03:40 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/23 02:21 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/23 00:51 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/22 23:30 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/22 21:57 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/18 18:26 linux-6.6.y 79643295eba1 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/18 02:30 linux-6.6.y 79643295eba1 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/17 12:27 linux-6.6.y 79643295eba1 95928915 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/16 17:01 linux-6.6.y 79643295eba1 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/14 22:52 linux-6.6.y 79643295eba1 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/14 04:04 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/13 21:04 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/13 17:36 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/13 11:28 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/13 10:05 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/13 05:07 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/12 11:33 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/12 10:14 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/12 08:01 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/11 18:10 linux-6.6.y 8b73de7da85f b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/11 10:21 linux-6.6.y 8b73de7da85f 1fe56c0a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/10 17:09 linux-6.6.y 8b73de7da85f 1fe56c0a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/06 08:53 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/03 11:24 linux-6.6.y 8b73de7da85f 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/09/02 03:39 linux-6.6.y a4a971135a2f 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/31 09:41 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/31 05:17 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/26 21:21 linux-6.6.y dc6160265ffc a2b77b9e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/24 16:54 linux-6.6.y dc6160265ffc b55bd4c3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/23 00:33 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/22 12:12 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/21 19:14 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/21 16:58 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/21 16:56 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/21 14:26 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/20 21:53 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/20 18:02 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/15 03:08 linux-6.6.y d27334b2888c 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/14 17:00 linux-6.6.y d27334b2888c 6f9b3e89 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/14 00:36 linux-6.6.y d27334b2888c b13552fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/13 03:35 linux-6.6.y d27334b2888c 359b2492 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/12 23:57 linux-6.6.y d27334b2888c 359b2492 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/12 09:42 linux-6.6.y d27334b2888c f8d35649 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/12 01:00 linux-6.6.y d27334b2888c 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/09 16:57 linux-6.6.y 6436c12a2ced 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/08 11:48 linux-6.6.y 6436c12a2ced 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/07 03:41 linux-6.6.y 80dfb0405055 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/08/06 04:52 linux-6.6.y aa0e49877a2e cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/22 20:24 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
* Struck through repros no longer work on HEAD.